This invention relates to insulated metal edge guards of the type which are applied to the trailing edges of swinging closures, such as an automobile's doors. More specifically the invention relates to a new method of making such edge guards and the edge guards produced by the method.
Edge guards of the general type to which the present invention relates are disclosed in a number of applicant's issued U.S. patents such as
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There are also a number of applicant's pending patent applications relating to this subject which are known to the Patent Office by virture of their pendency.
A door edge guard provides a protective function preventing the door edge from damage when the door is swung open against an object in the path of travel of the swinging door. Without door edge guards the painted door edges are subject to chipping, marring, and consequent adverse affects such as rusting and corrosion. This can lead to unsightly appearance and detract from the value of an automobile.
Applicant's inventions in insulated metal door edge guards serve to protectively insulate the metal of the edge guard channel from that of the door and in so doing minimize the possibility of electrochemical action occurring between the two metals, i.e. rusting. Applicant has also pointed out the advantages of having metal edge guards self-retaining.
Applicant has also developed edge guard designs in which the insulating material can be used to provide color coordination of the edge guard with the color of the swinging closure on which the edge guard is installed. For example in the case of a door edge guard, the exterior surface of the edge guard may be provided with a layer of insulating material of a desired color which coordinates with the color of the painted door.
Since automobile manufacturers offer a wide range of colors, and because each particular color-coordinated edge guard for a given door for a particular automobile model must be identified by its own unique part number even though all edge guards for that door would have the same shape, the provision of a range of colored door edge guards for the automobile industry is a monumental task.
The present invention provides a solution for efficiently performing this task.
One practice for manufacturing insulated metal edge guards comprises laminating a sheet of insulating material to a surface of a metal coil, slitting the coil into insulated strips of appropriate widths, and then roll-forming the slit insulated strips into U-shaped cross sections. With this procedure it is not possible for the insulating material to cover the side edges of the slit strip, and any covering of the side edges of the strip must be performed by a separate operation.
The availability of certain insulating materials, such as fluoridated vinyls, is only in sheets of certain minimum widths which are much larger than the widths of the individual strips which are formed into the U-shaped cross sections to form the insulated edge guards. Because the mix of color-coordinated edge guards will not be uniform, this procedure will contribute to costs associated with providing a range of color-coordinated insulated edge guards because it is necessary for the edge guard manufacturer to make certain minimum purchases from the manufacturer of the plastic material, and in widths greater than that of the metal strip forming the edge guard. Hence where a particular color may have only small usage, the edge guard manufacturer must carry a substantial inventory of that color and as can be appreciated some of this inventory may never be used, and the attendant costs constitute a waste of resources.
With the present invention the costs associated with providing such a range of edge guards are reduced to the advantage of the edge guard manufacturer, the automobile company, and the consumer who purchases an edge-guard-equipped automobile.
It has also been proposed to roll-form a metal strip of the appropriate width into a U-shaped cross section for the edge guard channel and then to run the U-shaped channel through an extruder to extrude plastic installation onto the formed U-shaped cross section. This procedure is satisfactory in the case of an edge guard where the U-shaped channel has been roll-formed into a straight shape. However where the edge guard must have a sweep so as to allow it to fit onto the trailing edge of a swinging closure which has a sweep, such as is often the case with an automobile door, it means that such sweep must be imparted by an additional operation after the plastic has been extruded onto the straight U-shaped cross section. Moreover, where multiple colors are involved the process becomes even more complicated.
The present invention improves the efficiency of manufacturing insulated metal edge guards, in general. It also especially improves the cost effectiveness of the production of insulated metal edge guards which are provided in a range of various colors for color coordination with a range of different automobile colors. The invention yields a very attractive and functional product of high quality. The inventory requirements for stocking bulk material in different colors are considerably simplified so that inventory costs are reduced.
One step in the method of the invention involves extruding plastic insulating material onto a metal strip. The automobile industry has experienced serious quality problems in extruding plastic onto metal parts, not door edge guards, and the present invention does not have any such problems associated with extruding plastic onto a metal strip which is to form a door edge guard.
Briefly the present invention comprises a process wherein plastic material is extruded onto a flat strip of metal which has a width corresponding to that which is to be used in roll-forming of an edge guard. The metal strip is pulled through an extruder in a straight line, and the plastic insulation is applied to the metal strip in an appropriate configuration. The strip is then wound into coils while still in the flat, and then the coils are unwound at a roll-former which roll forms the flat insulated strip into the desired U-shaped cross section.
The invention also provides the opportunity for creating unique edge guard constructions endowed with various decorative and functional features. By a selective extrusion of insulated plastic materials onto the metal it is possible to impart particular designs onto the metal by leaving selected portions of the metal uncovered. It is also possible to apply material to these voids, and for example a second extruder may be associated with the process to extrude material into the void which is left in a previously applied extrusion. By way of example the material which fills the void may have a light-reflective characteristic whereby a band of light-reflective material may appear in the edge guard so as to provide a light-reflective character useful at night.
Different color contrasts may be imparted to the metal channel of the edge guard while the protective and functional aspects of the edge guard are retained.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.